What is Colorectal Cancer? Causes, Signs, Stages & Treatment Options
Learn all about colorectal cancer — its early signs, risk factors, stages, and modern treatments. Discover how screening and lifestyle changes can help prevent it.
Why Colorectal Cancer Awareness Matters
Colorectal cancer
One of the most frequent and deadly cancers in the world is colon or rectal cancer. However, if detected early, it is very treatable and preventative.
Colon (colorectal) cancer begins in the large intestine, the lengthy tube that helps transport digested food to the rectum and then out of the body.
Colon cancer is caused by specific growths or polyps in the colon’s inner lining. Screening tests are available to healthcare providers to identify precancerous polyps before they develop into malignant tumors. If left untreated, colon cancer can spread to other parts of your body.
Cases in India
In 2022, there were an anticipated 14,61,427 incident cases of cancer estimated in India. One in nine Indians is likely to develop cancer at some point in their lives. The most common cancers in men and women, respectively, were lung and breast cancers. According to estimates, the number of cancer cases will rise by 12.8% in 2025 compared to 2020.
Causes & Risk Factors
- Age 50 and above
- Family history of colorectal cancer or polyps
- Chronic inflammatory bowel diseases (IBD)
- High intake of red or processed meat
- Low-fiber diet
- Sedentary lifestyle
- Obesity
- Smoking and alcohol use
- Type 2 diabetes
Symptoms
If early-stage colorectal cancer does cause symptoms, early warning signs may include sudden weight loss and/or narrow, ribbon-like stools. Other common early warning signs of colorectal cancer include:
- Rectal bleeding, either bright or dark red in color
- Narrow stools
- Anemia
- Persistent abdominal pain
- Weight loss
Note- Although these symptoms may be caused by other, less serious conditions, such as hemorrhoids, ulcers and Crohn’s disease, they should be discussed with a doctor. Blood in stool, even if it only appears intermittently, should never be ignored.
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- Constipation
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- Diarrhea
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- A feeling that the bowel doesn’t empty completely
Note- Patients who experience these possible symptoms of colorectal cancer for an extended period of time should visit a health care professional.
Diagnosis & Screening
Note- Early detection is safets way to prevent from colorectal cancer.
There are many screening tests that could help professionals in identifying colorectal cancer before symptoms appear, when treatment options may be more favorable. Additionally, several of these tests enable the detection and removal of polyps and adenomas before they develop into cancer. In other words, in addition to early detection, certain forms of colorectal cancer screening may enable cancer prevention.
Stool test-
Stool tests detect minute amounts of blood in feces (stool) that are invisible to the human eye. Both polyps and colorectal tumors can bleed. Individuals who test positive for these conditions are recommended to undergo a colonoscopy.
Colonoscopy
In this test, the rectum and entire colon are examined using a colonoscope.
Biopsy
A biopsy is typically performed if a suspected colorectal tumor is identified via a screening or diagnostic test. During a biopsy, the physician uses a specialized tool that is passed through the scope to extract a tiny sample of tissue. Less frequently, the diagnosis may require surgically removing a portion of the colon.
Molecular tests
The cancer cells will likely be examined for certain gene and protein alterations if the cancer has progressed, as this could assist determine whether targeted therapy medications are viable therapeutic alternatives. For instance, the KRAS, NRAS, and BRAF genes, along with other gene and protein alterations, are commonly examined for mutations in the cancer cells.
MSI and MMR testing
Additionally, colorectal cancer cells are usually examined for microsatellite instability (MSI), a high frequency of gene alterations. The mismatch repair (MMR) genes (MLH1, MSH2, MSH6, and PMS2) and the proteins they encode may also be tested for alterations. Another gene that is frequently examined is EPCAM.
Computed tomography (CT or CAT) scan
A CT scan generates finely detailed cross-sectional images of your body using x-rays. This test can assist in determining whether your liver, lungs, or other organs have been affected by colorectal cancer, as well as any adjacent lymph nodes.
Ultrasound
Ultrasound uses sound waves and their echoes to create images of the inside of the body.
Magnetic resonance imaging (MRI) scan
MRI can be used to look at abnormal areas in the liver or the brain and spinal cord that could be cancer spread.
Colorectal cancer Treatment
Treatment depends on cancer stage and location.
1. Surgery
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- Polypectomy for early-stage
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- Colectomy (colon) or Proctectomy (rectum)
2. Radiation Therapy
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- More common in rectal cancer
3. Chemotherapy
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- Used post-surgery or in advanced stages
4. Targeted Therapy
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- EGFR inhibitors
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- VEGF inhibitors
5. Immunotherapy
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- For tumors with genetic markers (MSI-H or dMMR)
Stages of Colorectal Cancer
| Stage | Description | 5-Year Survival Rate |
| 0 | In situ (confined to inner lining) | ~100% |
| I | Spread to muscle layers | ~90% |
| II | Through colon/rectal wall | ~70% |
| III | Reached nearby lymph nodes | ~50–60% |
| IV | Metastasized to liver/lungs/other organs | ~14% |
Prevention Tips
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- Eat a high-fiber, plant-rich diet
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- Avoid processed and red meats
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- Exercise regularly
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- Quit smoking and limit alcohol
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- Maintain healthy weight
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- Go for routine screenings
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- Manage conditions like diabetes or IBD
Final Thoughts
Colorectal cancer is largely preventable and treatable. With lifestyle changes and early screening, you can reduce your risk significantly. If you’re over 45 or have a family history, talk to your doctor about screening options today.
